Astigmatism

Close and distant objects can appear blurred, skewed or distorted

Astigmatism results from a cornea or natural lens which is not perfectly round. Due to this out-of-round shape, incoming light rays are focused unevenly onto the back of the eye.

Distant objects are sharply focused; close objects are out of focus.

Distant objects are sharply focused; close objects are out of focus.

What Is Astigmatism?

If you have astigmatism, the curvature of the transparent front part of your eye, called the cornea, may not be perfectly round. The shape of the cornea would be oblong – similar to an American football. In contrast, a normal cornea is evenly shaped like a basketball.

The asymmetry seen in astigmatism can consist of varying degrees of flatness and steepness in the cornea, depending on the type of astigmatism diagnosed. Due to this unevenness, incoming light rays are not put into sharp focus on the retina.

Regular astigmatism occurs when the cornea is uniformly curved more in one direction than the other

Irregular astigmatism happens when the curvature of the cornea is irregular and uneven across the surface of the eye

Next to this general classification, there are three types of astigmatism:

Myopic astigmatism

Hyperopic astigmatism

Mixed astigmatism

Instead of one sharp focal point like in normal vision, light fails to make a single, clear image on the retina, the layer of light-sensitive cells lining the back of the eye. Without a focused image on the retina, the information sent to the brain through the optic nerve can result in blurred, distorted and/or skewed images for both near and far objects.

Causes of Astigmatism

Astigmatism is not preventable

Like myopia and hyperopia, astigmatism is a refractive error: The eye cannot focus light properly onto the retina. It is usually the result of a cornea not being perfectly round.

Astigmatism may also exist if the natural lens is not round (lenticular astigmatism). It could also be a symptom of a disease known as keratoconus, which is recognizable because of a very irregular shape of the cornea.

Astigmatism is either present at birth, during early childhood, or could develop after a trauma injury or disease. If one or both parents have the condition, it increases the likelihood of suffering from it, too.

Depending on the extent of astigmatism, objects both near and far can appear blurred, skewed or distorted.

Symptoms of Astigmatism

Astigmatism can affect sight in different ways depending on how the cornea is shaped: Vision could be distorted in a horizontal, vertical and/or diagonal direction. This condition can occur independently or can be accompanied by myopia or hyperopia. Typical symptoms of uncorrected astigmatism can be eye strain and headaches, which mostly occur after reading or other prolonged visual tasks such as working on the computer. A very common symptom is squinting.

Regular astigmatism is a vision condition, not a harmful disease; the eye is still healthy. An ophthalmologist or optometrist can recognize astigmatism in a routine check-up exam. If you are diagnosed with astigmatism, it is likely that you will need glasses, contact lenses or laser eye surgery.

Options to Correct Astigmatism

If you suffer from astigmatism, there are several ways your vision could be corrected. You should consult with an ophthalmologist or optometrist to determine which options are available to you.

Glasses can be a convenient way to improve vision. Prescription glasses can fix refractive errors by altering the angle light rays enter the eye. For astigmatism, cylinder power at a specific axis orientation is added to the prescription. Depending on your style and budget, there is a large selection of frames and eyeglass lenses to choose from.

Contact lenses work under the same principles as glasses. Contact lenses differ in materials and duration of use. For astigmatism, there are toric contact lenses available that are shaped in a particular way. It is important to note that contact lenses are not without risks.

Laser eye surgery is another option to treat astigmatism. If your degree of astigmatism is moderate to high, SMILE, LASIK and PRK/LASEK may be recommended by your doctor as an option for you. These surgeries have high rates of success. Like all surgeries, refractive laser surgery is not without risks.

Intraocular lens exchange is another option that a doctor may recommend for correcting severe astigmatism in certain patients. This is a surgical procedure in which an artificial lens is implanted in place of the natural lens. Intraocular lens exchange is a common procedure for patients suffering from cataracts, while refractive or clear lens exchange refers to patients without cataract. Your doctor can recommend this if it is an option for you as well as which IOL is right for you and your refractive error. Like all surgeries though, it is not without risks.

Glasses can make simple tasks such as taking a picture easier.

Visual Aids

Living with glasses and contact lenses

Well over half the world’s population relies on glasses or contact lenses to see well. For many of these people, this may be the best option, and today, there are a variety of spectacle lens and contact lens options available for a wide range of vision needs.

However, many wearers have problems wearing glasses or contact lenses and find that their dependency on visual aids interferes with their daily lives.

Many people want to see – to see well without glasses or contact lenses. Laser eye surgery may provide a possible alternate solution to glasses and contact lenses. Consult with your eye doctor to determine the best option for your vision and daily life.

This website is only for basic information. It is not to be considered medical advice or a substitute for obtaining your own medical consultation, during which you will be informed also about possible risks, side effects and restrictions of refractive surgery. Not all treatment options are approved or offered in every country and approved labeling and instructions may vary from one country to another. This site is also not intended for patients and healthcare providers residing in the United States of America and Japan.

This is a code assigned to all external communications materials, to assist in tracking and monitoring during the internal approval process.

This is a code assigned to all external communications materials, to assist in tracking and monitoring during the internal approval process.

You will be routed to the official ZEISS Medical Technology website for Healthcare Professionals.

After confirmation, you will leave the ZEISS Medical Technology website for patients. The website you have requested is intended for healthcare professionals only and includes information about ZEISS medical technology products. The site may contain information on products or uses that are not approved in your country of residence.